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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b26990b1c6ceda01491b0bd977eff71d44a2e15d9a32565deba3366bae7a096d' 
  AND token = 'fx1HSo/ZpchmmrnB9uM7BPxLBoGVl9AcZiIlNvYUCpQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}